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UHV Lab

UHV
UHV cluster comprising several deposition and surface analysis chambers.

The IPS UHV (ultra-high vacuum) Analysis lab is a facility for in-situ growth studies combining a modular and extendable UHV cluster system for complementary surface analytics with several UHV growth chambers for in situ X-ray experiments during thin film and nanostructure formation.
Being situated in close proximity to the IPS beamlines and to a dedicated chemistry lab for sample preparation, the UHV Analysis lab allows for studying various nanosystems, optimizing the use of the beamlines, and ensures a fast feedback between complementary measurements and X-ray experiments.

The UHV cluster is a large ultra-high vacuum transfer system offering several docking stations for portable and stationary growth chambers. Samples with a maximum size of 25 mm can be inserted directly via three loadlocks. The central analysis and surface preparation chambers are accessible from all growth chambers. Here, samples can be prepared by Argon sputtering (limited to a surface area of 10x10 mm2) and annealing. They can be analyzed by standard surface characterization methods such as:

  • reflection high energy electron diffraction (RHEED),
  • low-energy electron diffraction (LEED),
  • Auger electron spectroscopy (AES),
  • X-ray photoelectron spectroscopy (XPS),
  • UHV atomic force microscopy (AFM),
  • UHV scanning tunneling microscopy (STM).


The UHV cluster is extendable and develops according to the demands of future experiments.

Cluster

Usage hint:

Clusterschema

Methods

In the UHV analysis lab, samples can be analyzed by several standard surface characterization methods including spectroscopical methods (XPS and AES), diffraction methods (LEED and RHEED) and scanning microscopy (AFM and STM). Here, an overview over the methods is given. As an example, measurements of a gold single crystal are shown.

XPS - X-ray Photoelectron Spectroscopy

XPS

X-ray photoelectron spectroscopy gives information about the chemical composition of a sample within the topmost 2 nm. The sample is illuminated by soft X-rays. Photoelectrons are emitted, giving information about the binding energies of the atoms.

 

AES - Auger Electron Spectroscopy

AES

Auger electron spectroscopy is another method to get information about chemical composition. Auger electrons are emitted from atoms, giving information about binding energies. One application of the method is to check a sample for surface contaminations, e.g. after contact with air.

 

LEED - Low Energy Electron Diffraction

LEED

Low energy electron diffraction gives information about the atomic ordering of a material, by bombarding it with a beam of low energy electrons. The pattern of the structure, created by the diffracted electrons; is shown on a screen.

 

RHEED - Reflection High Energy Electron Diffraction

RHEED

Reflection high energy electron diffraction is another method to examine the crystalline structure of the surface. Streaks indicate a smooth surface.

 

AFM - Atomic Force Microscopy

AFM

An atomic force microscope is a high-resolution scanning microscope which gives information about the surface morphology of a material on the atomic scale. The measured signal is the bending of a cantilever which is related to the force between a tip and the sample.

 

STM - Scanning Tunnel Microscopy

STM

Another method for imaging surfaces is the scanning tunnel microscopy. The measured signal is a tunnel current between a tip and the sample.

 

 

Chambers

Portable in situ MBE chamber

Portable chamber for in situ sputter deposition

 

Rare-earth MBE chamber

 

Real-time in situ X-ray investigations of dynamic processes during epitaxial growth and annealing of III-V semiconductor nanostructures (e.g. GaAsNW, InGaAsQD).

In situ X-ray experiments (XRD, XRR, EXAFS) during reactive and non-reactive sputter deposition of thin films.

Investigation of the interplay between the structure, morphology, magnetism and lattice dynamics in rare earth based epitaxial nanostructures.

Materials:
InGaAs  
Materials:
transition metal nitrides and carbides, metals, silicides          
Materials:
rare earth metals, silicides and oxides  

Special features:

RHEED

Special features:

modular chamber geometry, large angular range for XRD, RF and DC magnetron sputtering

Special features:

several high temperature evaporation sources, Tubo-e cell for oxides, in situ RHEED and MOKE measurements

Contact: Philipp Schroth

Research Project:

„III-V Semiconductor Nanostructures“

Contact: Bärbel Krause

Research Project: „Sputter deposition“

Contact: Svetoslav Stankov 

Research Group: „Nanodynamics“

Reference UHV chamber:

Slobodskyy et al., Rev. Sci. Instr. 83 (2012), 105112-105117 

Reference UHV chamber:

Krause et al., J. Synchr. Rad.19 (2012), 216-222 

Reference UHV chamber:

S. Ibrahimkutty et al., J. Sync. Rad. 22 (2015) 1 

 

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UHV-Chemistry Lab

The UHV- Chemistry Lab, which is directly connected to the UHV analysis laboratory, is optimized for the needs of thin film preparation such as sample surface preparation by etching, thin film deposition from solution, and cleaning of UHV components.
4
1
Storage and disposal containers
2
Ultrasonic bath
3
STM tip eatching divice

The chemistry lab is equipped with two fume hoods (standard & for strong acids). Storage space and disposal containers for acids, bases, and solvents are available.
 

Typical tasks:

  • Cleaning samples, holder and UHV-components in the ultrasonic bath
  • Chemical cleaning and etching of samples and components
  • Preparation of AFM and STM tips
  • HF etching of Si Substrates

 

Contact:

Lab Responsible: Dr. Bärbel Krause
Chemical Technical Contact: Annette Weißhardt